When configuring the iChat service in Server admin, the Start button may not appear in the iChat service configuration window. Other settings in the iChat service are dimmed (grayed out) and not editable.

This can occur if the /Library/Preferences/ichatserver.plist file has been deleted or is problematic. If the com.apple.ichatserver.plist file is deleted a new default version of this plist will be created.